They don’t kiai so much as kind of emit a low controlled angry scream/yell of several seconds, like a challenged, angry tomcat backed into a corner. This is a little different from the kiai I’m used to in Aikido, which is briefer and louder.

There is a comment in the 2nd Youtube above that “Matsumura and Matsui was both taught from Shimizu and Otofuji sensei”.

From Jodo and bayonet training, we get Aiki-Jo. O Sensei studied Jo and also learned bayonet techniques (jukendo) studied during the war. The consensus seems to be that the Aiki Jo techniques are actually designed to fit a WW1 era rifle with a bayonet

and that the Shinden Muso Ryu jodo grip and stance is quite different and would not fit a rifle with a bayonet; and that Saito Sensei was the one to write down and codify Aiki Jo as we know it now, leaving aside variants by Chiba and Nishio Sensei. Here is a clip of O Sensei defending against wooden rifles::